Possibly a bug or a feature request if this functionality was deliberate. Found via OTRS feedback:

https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=11611813#13999561

1. Toggle "Open app on Search tab" on in app settings.
2. Visit an article. Background app. Terminate app.
3. Article should restore when user relaunches the app within 5 hours of backgrounding as it does when that toggle is turned off.